Method for depositing inorganic/organic films

ABSTRACT

The present invention describes a method for applying a hybrid coating to a substrate. A coating according to the invention is formed by an inorganic component and an organic component. As a result, this coating has the hybrid character whereby the advantages of inter alia hardness are combined with flexibility. The invention also describes a device for the manufacture of a hybrid coating.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a 371 of PCT/NL03/00037 filed Jan. 17, 2003 whichclaims priority to and the benefit of Dutch Patent Application No.1019781 filed on Jan. 18, 2002, the contents of which are incorporatedherein by reference in their entirety.

FIELD OF THE INVENTION

The invention relates to methods for the manufacture of hybrid coatingsand to devices for the manufacture thereof.

BACKGROUND OF THE INVENTION

Hybrid materials that are built up from inorganic and organic componentsform a very important development within materials technology. Thesematerials combine the favorable properties of inorganic and ceramicmaterials, such as high mechanical strength and a high degree of wearand scratch resistance, with the favorable properties such as a highdegree of flexibility and impact resistance of organic materials. Hybridmaterials are formed from inorganic and organic components by bondingthese chemically with each other at a molecular level. They can be builtup as interwoven networks, as interwoven networks mutually bonded bycovalent chemical bonds and as interwoven networks having thereinhomogeneously distributed nanoparticles, which may or may not becovalently bonded, of, e.g., silicon, aluminum, zirconium, cesium,molybdenum or titanium oxides, and/or nitrides and/or carbides thereof.

Coatings manufactured from hybrid materials have a multiplicity ofapplications. It is possible to apply these materials in a patterned orcompletely covering manner. The combination of flexibility and hardnessmakes them ideal as coatings for plastics, in particular plastics fromthe ophthalmic industry. The low permeability (oxygen, water) of hybridmaterials provides for excellent barriers for food packaging and throughadaptation of the organic network, anti-adhesion layers for use inbathrooms or on kitchen utensils can be manufactured.

Currently, hybrid coatings are manufactured by means of wet-chemicaltechniques and deposited on the article of interest, a substrate, bymeans of dipping, spraying, flow-coating or spin-coating. However, thesemethods for the manufacture of hybrid coatings require several processsteps, long curing periods, prolonged preserving steps and the use oflarge amounts of solvents.

In the use of CVD (chemical vapor deposition) according to the priorart, it is difficult to deposit a hybrid material of a desiredcomposition under controlled conditions as a coating on a substrate. Theactivation in a chemical vapor of the separate components requirescompletely different conditions for the inorganic and for the organiccomponent. As a result, obtaining a fully integrated network of the twocomponents is very difficult.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a reactor vessel.

SUMMARY OF THE INVENTION

One object of the present invention is to provide methods for theapplication of a hybrid coating that obviate the problems of the priorart.

Another object of the present invention is to provide a hybrid coatinghaving improved scratch resistance.

Surprisingly, it has been found that an improvement for the wet-chemicalcoating method from the prior art can be obtained by making use ofplasma activated deposition of the hybrid material from a chemical vaporphase, whereby nanoparticles are captured in the coating. A hybridcoating consisting of an organic and an inorganic component havingimproved wear properties could be manufactured inter alia by a processof chemical vapor deposition or CVD with two separate plasmas.

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to a method for applying a hybrid coatingto a substrate, which coating comprises an inorganic and an organiccomponent and which inorganic component comprises nanoparticles, whereinprecursors for these components are activated in one or more plasmasources for plasma activated deposition of a chemical vapor phase andwherein the activated precursors are combined before they are depositedon the substrate from the chemical vapor phase for forming the coating.

The present invention further relates to a method for applying a hybridcoating to a substrate, which coating comprises an inorganic and anorganic component and which inorganic component comprises nanoparticles,wherein precursors for these components are activated in two or moreseparate plasma sources for plasma activated deposition of a chemicalvapor phase and wherein one of the two activated precursors passes theplasma for activation of the other precursor whereafter the activatedprecursors are combined before they are deposited on the substrate fromthe chemical vapor phase for forming the coating.

Further, the invention relates to a hybrid coating which is obtainedaccording to a method of the invention and to products which comprisesuch a hybrid coating.

The invention further provides a device for applying a hybrid coating ofan inorganic and an organic component to a substrate through plasmaactivated deposition of a chemical vapor phase, which comprises areactor space provided with a carrier for a substrate, and at least twoseparate plasma sources for forming the inorganic and the organiccomponent, the separate plasma sources being situated in the processingdirection such that the two activated precursors are combined beforebeing deposited on the substrate.

In addition, the invention provides a device for applying a hybridcoating of an inorganic and an organic component, which inorganiccomponent comprises nanoparticles, to a substrate through plasmaactivated deposition of a chemical vapor phase, which comprises areactor space provided with a carrier for a substrate, and at least twoseparate plasma sources for forming the inorganic and the organiccomponent, the separate plasma sources being situated in the processingdirection such that one of the two activated precursors passes theplasma for activation of the other precursor before being deposited onthe substrate.

A coating according to the invention is formed by an integrated networkof an inorganic component and an organic component. As a result, thiscoating has the hybrid character whereby the advantages of hardness arecombined with a high degree of flexibility.

A hybrid coating manufactured according to a method of the invention isbuilt up as interwoven networks having therein homogeneously distributednanoparticles which may or may not be covalently bonded, of, e.g.,silicon oxides, metal oxides, silicon carbides, metal carbides, siliconnitrides and/or metal nitrides or combinations thereof. Thenanoparticles preferably have a diameter of less than 450 nm, morepreferably a diameter of less than 100 nm.

Hybrid materials according to the present invention may be built up froma large variety of inorganic and organic components which are chemicallybonded to each other at a molecular level. Thus, a hybrid coatingaccording to the invention can comprises an inorganic (for instanceglassy) network that has been modified with organic residue groups. Sucha structure is sometimes referred to as Ormocer. A hybrid coatingaccording to the invention having the structure that is designated asOrmocer can comprise an organically modified matrix based on a metaloxide, metal carbide and/or metal nitride or a silicon oxide, siliconcarbide and/or silicon nitride. Through the character of the plasmaactivated deposition according to the invention, the organic residuegroup can take any form in which carbon, silicon and optionally oxygenatoms or carbon, metal and optionally oxygen atoms are combined witheach other.

For the metal, any metal can be chosen. Preferably, the metal isselected from the group consisting of aluminum, cadmium, cerium,chromium, cobalt, gold, copper, lanthanum, lead, manganese, molybdenum,nickel, osmium, palladium, platinum, tin, titanium, vanadium, tungsten,iron, silver, zinc, zirconium, alkali metals and alkaline earth metals.More preferably, the metal is Al, Mo, Ti, Zr, Cs, Pt or Sn.

An alternative coating that can be realized by the use of a methodaccording to the invention comprises organic polymers which have beenbonded together to form a continuous or discontinuous matrix, andfurther comprises inorganic very small particles (nanoparticles) ofmetal or silicon oxides or inorganic network structures. Such a coatingstructure is sometimes referred to as a Ceramer.

Another alternative coating that can be realized by the use of a methodaccording to the invention comprises a metallic matrix which furthercomprises inorganic very small particles (nanoparticles) of metal orsilicon oxides or inorganic network structures.

A coating that is realized in any case by the use of a method accordingto the invention comprises the inorganic network structure with organicresidue groups of the structure that are based on an Ormocer but inwhich further very small inorganic particles of metal or silicon oxides,which may or may not be chemically bonded, are present. Such a structureis sometimes referred to by the term Nanomer.

The different constituents or components of a hybrid coating accordingto the invention are preferably formed from precursor molecules in aprocess of precursor activation. During this activation, the precursormolecules are dissociated. Dissociation of the precursors can be done bymeans of thermal dissociation, laser dissociation or other suitablemethods that are known in the art. A particular preference is expressedfor a method whereby the precursor molecules are activated by means of aplasma. According to the present invention, with great preference, theactivation of the organic and inorganic precursors takes place inseparate plasmas.

For the formation of an inorganic component, in many cases a precursorfor a metal oxide, metal nitride, or metal carbide or a silicon oxide,silicon nitride or silicon carbide will be used. Since in the plasmastrong dissociative activation takes place, as precursor for aninorganic component, compounds that comprise a direct metal-carbon, ametal-hydrogen, a metal-nitrogen, a metal-halide, or a metal-oxygenbond, such as organometal or metallorganic compounds, metal alkoxydes,metal halides, metal carboxylates, or metal-8-diketonates can be chosen.It is also possible to use, as precursor for an inorganic component,compounds which comprise a direct silicon-carbon, a silicon-hydrogen, asilicon-nitrogen, a silicon-halide, or a silicon-oxygen bond, such asorganosilicon compounds, silicon alkoxydes, silicon halides, siloxanes,silanes, silazanes, silicon carboxylates, or silicon-β-diketonates.

In case an organometal compound is selected, for the metal, any metalcan be selected. Preferably, the metal is selected from the groupconsisting of aluminum, cadmium, cerium, chromium, cobalt, gold, copper,lanthanum, lead, manganese, molybdenum, nickel, osmium, palladium,platinum, tin, titanium, vanadium, tungsten, iron, silver, zinc,zirconium, alkali metal and alkaline earth metal. Preferably, the metalcompound is selected from the group consisting of a metal alkoxyde,carboxylate or -β-diketonate. With greater preference, the organometalcompound is a metal alkoxyde, carboxylate or β-diketonate in which themetal is Al, Mo, Ti, Zr, Cs, Pt or Sn.

For the formation of the nanoparticles, preferably a part of theinorganic component is deposited in the form of nanoparticles. Thesenanoparticles are formed through substantially complete dissociation ofthe inorganic precursors, such as, for instance, the metal or siliconalkoxydes, and condensation of activated molecules to virtuallycrystalline nanoparticles. Once captured and covalently bound, or not,in the hybrid coating, these nanoparticles offer the advantage that theyimpart very high scratch resistance to the hybrid coating. Preferably,in an embodiment according to the present invention, nanoparticles areformed having a diameter between 1 and 200 nm. With greater preference,the nanoparticles possess a diameter between 1 and 50 nm.

When an organic molecule is introduced into a plasma, the monomer drawsenergy from the plasma through non-elastic impacts and it is activatedand fragmented into activated smaller molecules. The activated monomerscombine with each other, thereby forming larger molecules, eventuallyresulting in a polymer. Because the plasma will fragment most organiccompounds, plasma polymers can be deposited from virtually any organicmonomer. Plasma polymers are in most cases highly branched andcrosslinked, in most cases they are insoluble and adhere to solidsurfaces. The chemical and physical properties of the plasma polymersdepend on the precursor used, which is mostly introduced into the plasmain gas or vapor form, and the type of discharge (e.g. direct current,radiofrequency waves or microwaves) and the energy power introduced.

As precursor for an organic component, a multiplicity of organiccompounds can be used. In fact, basically all conceivable organicsubstances can be activated as precursor in the organic plasma, and thecomponents that are formed therefrom can be used in coatings accordingto the present invention.

As precursor for an organic component, in general, alkanes, alkynes,alkenes, arenes and optionally wholly or partly (cyclo)alkyl-, aryl-,aralkyl-, allyl-, methoxy-, halogen-, hydroxy-, amino-, nitro-, cyano-,epoxy, glycidoxy, (meth)acrylato substituted derivatives thereof aresuitable for use in the present invention. Preferably, short chainalkanes (C₁₋₆), acrylate, styrene or carbon-fluorine compounds (CF₄,C₂F₄, C₂F₆ and C₄F₁₀) are used as organic precursor.

In the present description, the term alkanes is understood to refer toacyclic, branched or unbranched hydrocarbon of the general formulaC_(n)H_(2n+2) having from 1 to 10, preferably from 1 to 8 carbon atoms,such as ethane, methane, propane and pentane.

The term alkenes is understood to refer to acyclic branched orunbranched hydrocarbon having one double carbon-carbon bond and ageneral formula of C_(n)H_(2n) having from 1 to 10, preferably from 1 to8 carbon atoms. This is also understood to include the acyclic branchedor unbranched hydrocarbons having more than one double carbon-carbonbond such as alkadienes, alkatrienes, etc.

The term alkynes is understood to refer to acyclic branched orunbranched hydrocarbons having a triple carbon-carbon bond and havingthe general formula C_(n)H_(2n-2) having from 1 to 10, preferably from 1to 8 carbon atoms. This is also understood to include the acyclicbranched or unbranched hydrocarbons having more than one triplecarbon-carbon bond, such as the alkadiynes, alkatriynes, etc.

In the present description, the term alkyl group refers to a monovalentgroup derived from an alkane through the removal of a hydrogen atom fromone of the carbon atoms and comprises a straight chain or branched chainhaving from 1 to 10, preferably from 1 to 8 carbon atoms. The term(cyclo)alkyl group refers to an alkyl group or a cyclic alkyl radical.These last also encompass saturated or partly saturated monocyclic,bicyclic or tricyclic alkyl radicals in which each cyclic group contains3 to 8 carbon atoms. Examples of such radicals are methyl, ethyl,n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, pentyl,iso-amyl, hexyl, octyl, cyclopentyl, cyclopentenyl, cyclohexenyl,cyclohexyl, cyclopentadienyl and cycloctadienyl.

The term aromatic group refers to arenes and substituted derivativesthereof, such as benzene, naphthalene, toluene and should be understoodas comprising the heteroaromatic structures, such as thiophene andpyridine. Arenes refer to the monocyclic and polycyclic aromatichydrocarbons. The term aryl refers to an aromatic or heteroaromatic ringsystem obtained from arenes by removal of a hydrogen atom from a ringcarbon atom, such as a phenyl, naphthyl or anthracene group, optionallysubstituted with alkyl, methoxy, halogen, hydroxy, amino, nitro, orcyano.

The term aralkyl means an alkyl as defined above, in which one hydrogenatom has been replaced with an aryl group as defined above. Allyl refersto propene radicals (CH₂)₂CH. Halogen refers to fluorine, bromine,iodine or chlorine.

Organosilicon compounds, such as polydimethylsiloxanes (PDMS) withterminal trimethylsiloxy, hydroxy or hydride groups,hexamethyldisilazane (HMDSN), hexamethyldisiloxane (HMDSO),1,3-divinyltetramethyl disiloxane (DVS), vinylpentamethyldisiloxane(VPMDSO), 1,1,3,3-tetramethyldisiloxane (TMDSO), 1,3,5,7-tetramethylcyclotetrasilane (TMTSO),2,4,6,8-tetravinyl-2,4,6,8-tetramethylcyclotetrasiloxane (TVTMTSO),diacetoxy-di-tert-butoxysilane (DADBS), triethoxysilane (TRIES)methyltrimethoxysilane (MTS), 1,2-bis(trimethylsilyloxy)ethane (TMSE),tetramethoxysilane (TMOS), tetraethoxysilane (TEOS),octamethyltrisiloxane (OMCTS), or tripropylsilane (TPS), organometalcompounds and metal organic compounds also find very suitableapplication in embodiments according to the present invention and can beused with advantage as precursor of the organic as well as of theinorganic component.

Poly(p-xylylene), or parylene-N, can also be used with advantage asprecursor for the organic component, as well as dimers, such asdi-p-xylylene, or monomers, such as p-xylylene, and optionallyfunctionalized compounds obtained or derived therefrom.

By ‘optionally functionalized’ is meant that these compounds may bechemically derivatized, so that, incorporated into the coating, theyimpart to this coating a functional property such as biocompatibility,hydrophobicity, anti-reflection or anti-stick properties. This can berealized, for instance, by the use of halogen functionalizedderivatives, while the starting compounds have been halogenated with,for instance, fluorine or chlorine. Examples of functionalized compoundsthat can be used as precursor for the organic components are PPXC([—CH₂—C₆H₃Cl—CH₂—]₂ as dimer), and AF-4 (CF₃—C₆H₄—CF₃).

The ratio of inorganic precursor/organic precursor can be varied, toobtain a more, or less, flexible material.

In the present invention, a plasma is understood to mean a gaseous orvaporous composition of constituents which under the influence ofelectric energy generated by a plasma source, has been brought to (gas)discharge. The space in which this discharge is effected is limited byan electric field which is generated by an electric power source and bya physical separation, if any is present, such as, for instance, a glasstube, and is called a plasma source.

In a wider sense, plasma source in the present invention is understoodto mean an electric power source and the electrodes for generating anelectric field as well as the space limited by this field, for dischargeand activation of a gaseous or vaporous composition of constituents andany physical separation present. If in the present descriptionproperties or embodiments are assigned to the plasmas, these propertiesor embodiments also hold for the plasma source as far as they relate toit, and vice versa.

A coating according to the invention with a Nanomer structure can bevery suitably obtained by the use of a single plasma source.

However, in the present invention, preferably at least two plasmasources of a different nature are used. Thus, preferably, in addition toa high electron density plasma source, a low electron density plasmasource is used. However, two or more plasma sources of the same type canalso be used in the present invention.

A high electron density plasma source typically has an electron densitybetween 5×10¹⁶-5×10¹⁹ electrons/m³. An example of such a plasma sourceis an ICP (inductively coupled plasma) plasma source or an ECR (ElectronCyclotron Resonance). A low electron density plasma source typically hasan electron density between 5×10¹⁰-5×10¹⁶ electrons/m³. An example of alow electron density plasma source is a CCP (capacitively coupledplasma) plasma source or a DC (direct current) plasma source.

Electron densities can be determined with methods known for thatpurpose, such as the Langmuir probe method, microwave or laserinterferometry, or Thomson scattering.

A plasma composition in the present description is defined as a gaseousor vaporous composition which is supplied to the electric fieldgenerated by the plasma source to obtain the plasma regardless ofwhether this composition has already been brought to discharge.

A general embodiment of a device according to the invention formanufacturing a hybrid coating comprises a reactor space in which thechemical vapor deposition onto the substrate takes place and which islimited by a reactor vessel. The reactor space is provided with acarrier for a substrate. The device further comprises at least twoseparate plasma sources for the activation of the inorganic and organicprecursor components.

Different preferred embodiments of such a device are suitable formanufacturing hybrid coatings according to the invention. A preferredembodiment is represented in FIG. 1. There is shown a reactor vessel (1)provided with a closed glass tube (16) at the top thereof, and an opencommunication (9) is provided between the reactor space (15) and thespace limited by the glass tube (16).

Around the glass tube (16) an electric winding is arranged, which isconnected to a first electric power source. This plasma source (4) canfurther be provided with a first precursor inlet (2) and a secondprecursor inlet (3) through which supply of a precursor of an inorganiccomponent, argon gas and optionally oxygen can take place.

In reactor space (15), by means of a second plasma source (6), a plasmamay be situated through provision of electrodes (1, 10), one of theelectrodes (10) being also carrier for a substrate (10). This plasmasource can be provided with its own precursor inlet (12).

The whole set-up can be suspended by way of a suspension device (14) andbe provided with a grounding (13). Through the heating elements (8) thetemperature of the reactor can be raised if required. Upon switching onof the first electric power source, in a high electron density plasmasource (4) a plasma (5) is generated for activating the precursor of aninorganic component. Upon switching on of a second electric powersource, in the low electron density plasma source (6) a plasma (7) isgenerated to activate a precursor for an organic component. Through thesupply of gas through precursor inlets (2) and/or (3) and throughsimultaneous extraction of chemical vapors through outlet (11), theplasma of the high electron density plasma source (5) can move towardsthe reactor space (15) where it is directly captured in the low electrondensity plasma (7). Here, a further reaction of the high electrondensity plasma can take place, so that additional energy can be suppliedto the inorganic component. As a consequence, the substrate provided oncarrier (10) is then covered with a combination of organic and inorganiccomponents and the additional energy supply provides for the growingcoating being made denser. A certain fraction of the inorganic componentwill have condensed to very small particles and will be deposited assuch.

This embodiment, however, concerns one of the possible embodiments andshould not be construed as limiting the scope of the present invention.It will be clear to those skilled in the art that variations on theabove described device are possible. Thus, it is possible to uncouplethe high electron density plasma and the low electron density plasma.The design of the electric power sources, the manner in which theelectric power source is arranged and the charge carriers are mutuallycoupled, and the distance between plasma and carrier for the substrateare not critical and can be adjusted. Suitable configurations forobtaining desired material properties can be determined throughoptimization.

Preferably, the coupled plasmas applied are high-frequency plasmas. Afrequency of between 0.01 MHz and 10 GHz in this connection is verysuitable for inducing discharge in the plasmas. It is greatly preferredthat a frequency of between 1 and 50 MHz be used.

The plasmas can be situated in the direct vicinity of the substrate orat some distance therefrom. The situation where the substrate isarranged directly between the two electrodes (1, 10) of the low electrondensity plasma source (6) or in the electric field of a high electrondensity plasma source (4), in which cases a so-called direct plasma isinvolved, results in a higher thermal load on the substrate under theinfluence of exposure to high energy particles. Although not allsubstrates are suitable for high thermal loading, direct plasmas canstill be used with great advantage in the present invention.

Preferably, in a device according to the invention, at least one plasmasource is situated at some distance from the substrate. Such “remote”plasmas therefore find particularly suitable application in the presentinvention.

To pass the particles activated in the remote plasma to the substrate,it is practical that a device according to the invention be providedwith transport means for a vapor phase. Such means can comprise“passive” means such as gravity, whereby the remote plasma, thesubstrate and the field of gravity are in one line. Also, activetransport means for a vapor phase can be included in a device accordingto the invention. Such active systems can consist of a pressure gradientor an active air, vapor or gas stream in the processing direction.‘Processing direction’ as used herein is the direction in which aplasma-activated particle must travel to reach the substrate and todeposit thereon.

An active air or gas stream can be generated by introducing air, vaporor gas with excess pressure into the device. To that end, a carrier gassuch as N₂, argon, or any other suitable unreactive gas, or a gasinvolved in the activation reaction, such as oxygen, can be used.

Alternatively, an active air, vapor or gas stream can be generated byextracting air, vapor or gas from the device. The manner in which thepressure gradient or the active air, vapor or gas stream is obtained isnot of preponderant importance in methods and devices of the invention.Preferably, the transport means for a vapor phase are realized byintroducing gas with excess pressure into the device and simultaneouslyextracting vapor from the device, so that a reduced pressure, withrespect to atmospheric pressure, is created in the device. This furtherpromotes a stable plasma discharge. A pressure between 0.01 and 1000mbara finds suitable application in embodiments according to the presentinvention. Good results have been obtained at a pressure in the devicebetween 0.1 and 50 mbara.

The plasmas that can be used in the present invention are aimed atforming from precursor molecules, reactive intermediates that can bedeposited on the substrate. Depending on the energy supplied to theplasma source, the precursor will be activated into a reacted anddissociated intermediate. The extent of dissociation can be set bychoosing the level of the plasma source energy. Suitable powers inplasmas that are used in embodiments of the present invention aregenerally between 10 and 2500 Watts, with voltages varying between 0.001and 5000 Volt.

Preferably, the plasma is pulsed to liberate the particles capturedtherein from the plasma volume and to effect deposition on the substrateto be coated. Preferably, a pulse frequency of 1 to 100 Hz is used. Withgreater preference, a pulse of approximately 25 Hz (with a duty cyclebetween 5 and 10%) is used.

Concentrations of precursors in a plasma composition according to theinvention are generally between 1 and 25 vol. %. Optionally, in additionoxygen can be supplied to the plasma composition to a concentration ofapproximately 80%.

Besides precursor molecules, the plasma composition comprises anunreactive carrier gas such as N₂ or a noble gas such as argon, helium,neon, krypton, radon and/or xenon or a combination of these gases tosupplement the volume. The plasma volume is preferably supplemented withargon gas. The formation of the inorganic precursor plasma is preferablyeffected by bringing the mixture of oxygen, precursor molecules andargon gas to electric discharge in a plasma source. The reactionsthereby occurring lead to dissociation or activation of the precursormolecules.

Upon leaving the plasma, the activated intermediates preferably movesubstantially towards the substrate on which they can deposit and ifpossible substantially polymerize/condense. A considerable advantage ofthe present invention is that it is possible according to the proposedmethod to adjust the composition, and hence the properties of the hybridcoating, to any desired specification or application.

The ratio of inorganic to organic components, the density of the hybridmaterial that is manufactured in this way and the amount ofnanoparticles present can be fully controlled. In this way, manydifferent specific properties can be imparted to the material. Also, tothe different plasmas additives can be added, enabling specificproperties to be imparted to a coating according to the invention. Thefollowing properties can be recognized and specifically imparted:

-   -   Anti-soiling action can be achieved by the use or addition of        halides in the plasma in that these will reduce the surface        energy of the eventual coating.    -   A high degree of wear resistance is achieved by incorporating        nanoparticles of silicon oxides or metal oxides in the coating.    -   Enhanced barrier action can be achieved by depositing as large        an amount of inorganic material as possible. Also, there is the        possibility of alternately stacking organic and inorganic layers        onto each other and in this way enhancing the barrier action.    -   The color of the coating can be varied by the use of specific        layer thicknesses or by vapor depositing pigments.    -   The structure or the porosity of the coating can, if necessary,        be adjusted at will by choosing the plasma parameters such that        to a greater or lesser extent a bias voltage is created on the        substrate. Further, it is possible to start from a DC (direct        current) plasma source.    -   The hydrophobicity or hydrophilic character of the coating can        be varied by the use of, respectively, carbon-fluorine compounds        and the addition of extra hydrogen atoms in the form of H₂ gas        to a plasma. What can thus be achieved, for instance, is that        optical materials (spectacle glasses, lenses) get fogged less        easily.

Any substrate is suitable to be clad with a coating according to theinvention provided that the activated intermediates can adhere to it.Suitable substrates for applying a coating according to the presentinvention are substrates of plastic, including glass-replacing plastic.Such glass-replacing plastics can be used to replace spectacle glass, insolar cells and as material for lenses and car headlight glass. Alsosubstrates of metal, glass, ceramics, paper or textile can be clad witha coating according to the present invention.

A coating according to the invention also finds suitable application asa barrier coating such as it is used, for instance, in P-LEDs (polymericlight emitting diode) in the semiconductor industry, but also inpackaging material in the food industry, such as improved PET bottles orcrisps bags. Virtually any application where a material having a higherwear resistance or scratch resistance is desired can benefit from thecoating and the method of preparation which is provided in the presentinvention.

The thickness of the coating can be adjusted by varying the vapordeposition time (the period in which the substrate is exposed to thechemical vapor phase). Thicker coatings are achieved after longer vapordeposition times. Optionally, the deposition rate of the differentactivated components can be increased by supplying more energy to theplasmas or by increasing the gas or vapor stream through the device.

The substrate can optionally be cleaned or otherwise treated to improvethe adhesion of activated intermediates, and hence the entire coating.Such treatment methods are known in the art and comprise treatment with,for instance, HF, NH₄OH or H₂SO₄, or with the aid of a plasma accordingto methods known for that purpose.

EXAMPLE 1 Method for CVD of a Hybrid Coating

With the aid of a device as represented in FIG. 1, a hybrid coating wasmanufactured on a plastic substrate, e.g. PC (polycarbonate) or ABS(acrylonitrile butadiene styrene). As precursor for the inorganiccomponent, tetraethoxysilane was used. A high electron density plasma toactivate this component was composed on the basis of 4% precursor, 40%oxygen, supplemented with argon and a total flow of 0.5 SLM (Standardliter per minute).

As precursor for the organic component, separately, both1,2-bis(trimethylsilyloxy)ethane (TMSE), tetraethoxysilane (TEOS) andtri-n-propylsilane (TPS) were used. A low electron density plasma toactivate this component was composed on the basis of 15% precursor(TMSE), 0% oxygen, supplemented with argon and a total flow of 0.1 SLM.Further, this plasma comprised products coming from the high electrondensity plasma.

The high electron density plasma was generated by setting a power of 300watt, resulting in a high-frequency alternating voltage of at most 2000Volts (RF peak) and thus allowing the gases to discharge.

The low electron density plasma was generated by applying an electricvoltage of 150 volts (DC bias) between the electrode/carrier (10) andthe reactor casing (1) and to allow this to discharge with a frequencyof 13.56 MHz (set power of 300 Watt).

The high electron density plasma was pulsed with a frequency of 25 Hz(with a duty cycle between 5 and 10%). The pressure in the reactorvessel was lowered to 1.5 mbara.

The reactor operated at room temperature. During the vapor depositionprocess, some heating of the substrate occurred as a result of theplasma but higher temperatures than 150° C. were not observed.

In 10 minutes time, a coating was obtained of a layer thickness between1 and 1.5 micrometer. FTIR analyses show inter alia Si—C, Si—O and C—Hbonds. Taber tests to measure the wear give a comparable result to thatobtained with hybrid coatings applied via wet chemical techniques. Thetransmission in the visible range of the obtained coatings is greaterthan 70%.

1. A method for applying a hybrid coating to a substrate, which coatingcomprises an inorganic and an organic component and which inorganiccomponent comprises nanoparticles, wherein precursors for said organicand inorganic component are activated in two or more separate plasmasources for plasma activated deposition of a chemical vapor phase,wherein said activated precursors are combined before they are depositedon the substrate from the chemical vapor phase for forming the coating,and wherein the inorganic component is generated in a high electrondensity high-frequency plasma and wherein the high electron densityhigh-frequency plasma is pulsed.
 2. A method according to claim 1,wherein one of the two activated precursors passes the plasma foractivation of the other precursor, whereafter said activated precursorsare combined.
 3. A method according to claim 2, wherein the activatedinorganic precursor passes the plasma for activation of the organicprecursor.
 4. A method according to claim 2, wherein the activatedorganic precursor passes the plasma for activation of the inorganicprecursor.
 5. A method according to claim 1, wherein the organiccomponent is generated in a low electron density high-frequency plasma.6. A method according to claim 5, wherein the low electron densityhigh-frequency plasma is pulsed.
 7. A method according to claim 1,wherein the precursor for the inorganic component comprisesmetal-carbon, metal-hydrogen, metal-nitrogen, metal-halide, and/ormetal-oxygen bonds.
 8. A method according to claim 6, wherein theprecursor for the inorganic component comprises an organometal compound,a metal organic compound, metal alkoxide, metal carboxylate, ormetal-β-diketonate.
 9. A method according to claim 7, wherein the metalcomprises aluminum, titanium, zirconium, molybdenum, cesium, tin and/orplatinum.
 10. A method according to claim 1, wherein the precursor forthe inorganic component comprises silicon-carbon, silicon-hydrogen,silicon-nitrogen, silicon-halide, and/or silicon-oxygen bonds.
 11. Amethod according to claim 10, wherein the precursor for the inorganiccomponent comprises an organosilicon compound, silicon alkoxide,siloxane, silane, silazane, silicon carboxylate, orsilicon-β-diketonate.
 12. A method according to claim 1, wherein theprecursor for the organic component comprises alkanes, alkynes, alkenes,arenes, and optionally wholly or partly (cyclo)alkyl-, aryl-, aralkyl-,allyl-, methoxy-, halogen-, hydroxy-, amino-, nitro-, orcyano-substituted derivatives thereof.
 13. A method according to claim1, wherein the precursor for the organic component comprises short chainalkanes, acrylate, styrene or carbon-fluorine compounds.
 14. A methodaccording to claim 1, wherein the precursor for the organic componentcomprises an organosilicon compound, organometal compound, metal organiccompound or p-xylylene, and/or optionally functionalized compoundsderived therefrom.
 15. A method according to claim 1, wherein theseparate activation sources are situated in a reactor in which apressure of between 0.01 and 1000 mbar prevails.
 16. A method accordingto claim 1, wherein the separate activation sources are situated in areactor in which a pressure of 0.1 to 50 mbar prevails.
 17. A methodaccording to claim 1, wherein the plasmas are formed by bringing amixture of precursor material, argon gas and optionally oxygen toelectrical discharge.
 18. A method according to claim 1, wherein to thelow electron density plasma, also vapor coming from the high electrondensity plasma is supplied.
 19. A method according to claim 1, whereinto the high electron density plasma, also vapor coming from the lowelectron density plasma is supplied.
 20. The method of claim 1, whereinthe high electron density high-frequency plasma is pulsed at a pulsefrequency of from about 1 to about 100 Hz.
 21. The method of claim 1,wherein the pulse frequency is 25 Hz with a duty cycle between about 5%to about 10%.